Tectonic-sedimentary evolution of the northern margin of Gondwana during Late Palaeozoic – Early Cenozoic time in the Eastern Mediterranean region: evidence from the Central Taurus Mountains, Turkey.

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Abstract

The Taurus Mountains are an E-W trending mountain range in southern Turkey, with an
elevation of up to 3500 m. In the south central Taurides, the Beysehir-Hoyran-Hadim
nappes, a series of thrust sheets of Palaeozoic to Early Cenozoic age, are emplaced onto
a relatively autochthonous Tauride platform, known as the Geyik Dag. These thrust
sheets consist of a variety of discrete tectonostratigraphic units of continental platform,
rifted margin and oceanic (ophiolitic) origin. It is generally accepted that the relatively
autochthonous Tauride platform and the associated thrust sheets restore as a north-facing
passive margin during Jurassic–Cretaceous time; however, the Triassic and earlier
tectonic setting of the Tauride units is contentious. New data (mainly structural and
sedimentological) presented here tests contrasting tectonic models of Late Palaeozoic –
Early Mesozoic Tethys ocean evolution. Also, new light is shed on the Late Cretaceous
and Early Cenozoic break-up and emplacement of the Tauride units during closure of
Tethys.
The Late Palaeozoic Tauride stratigraphy consists of shallow-marine carbonate,
sandstone and mudstone, characteristic of a proximal passive margin. Detailed
stratigraphic logging, facies interpretation, compositional analysis and geochemical
evidence supports a passive margin setting, with sediment derived from the Tauride
“basement”. Early – Middle Triassic mixed siliciclastic/carbonate sediments are
interpreted as representing rifting and subsidence. Late Triassic coarser terrestrial
clastics (Cayir Formation) are considered to represent a pulse of rift-related flexural
uplift. Sediment provenance during this time was from the underlying Tauride platform
to the north of the studied area. A previous hypothesis that a Palaeotethyan ocean closed
in this area during latest Triassic “Cimmerian” orogenesis is discounted. Instead,
structural and sedimentary data suggest that all of the deformation relates to Late
Cretaceous – Early Cenozoic southward emplacement of the Beysehir-Hoyran-Hadim
nappes. A first phase of thrusting (thin-skinned) emplaced ophiolite and distal margin
units, whilst a second phase (thick-skinned) thrust platform lithologies southwards onto
the foreland. Evidence is also summarised, notably from the Palaeozoic – Early
Mesozoic Konya Complex to the north, which illustrates the relation of the Tauride
platform to other geological terranes in Turkey and elsewhere in the Alpine-Himalayan
orogenic belt. This thesis increases understanding of large-scale tectonic and
sedimentary processes associated with continental margins and orogenic development.